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); 142 143 /* 144 * sget() wrappers to be called from the ->get_tree() op. 145 */ 146 enum vfs_get_super_keying { 147 vfs_get_single_super, /* Only one such superblock may exist */ 148 vfs_get_single_reconf_super, /* As above, but reconfigure if it exists */ 149 vfs_get_keyed_super, /* Superblocks with different s_fs_info keys may exist */ 150 vfs_get_independent_super, /* Multiple independent superblocks may exist */ 151 }; 152 extern int vfs_get_super(struct fs_context *fc, 153 enum vfs_get_super_keying keying, 154 int (*fill_super)(struct super_block *sb, 155 struct fs_context *fc)); 156 157 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_single_reconf(struct fs_context *fc, 164 int (*fill_super)(struct super_block *sb, 165 struct fs_context *fc)); 166 extern int get_tree_keyed(struct fs_context *fc, 167 int (*fill_super)(struct super_block *sb, 168 struct fs_context *fc), 169 void *key); 170 171 extern int get_tree_bdev(struct fs_context *fc, 172 int (*fill_super)(struct super_block *sb, 173 struct fs_context *fc)); 174 175 extern const struct file_operations fscontext_fops; 176 177 /* 178 * Mount error, warning and informational message logging. This structure is 179 * shareable between a mount and a subordinate mount. 180 */ 181 struct fc_log { 182 refcount_t usage; 183 u8 head; /* Insertion index in buffer[] */ 184 u8 tail; /* Removal index in buffer[] */ 185 u8 need_free; /* Mask of kfree'able items in buffer[] */ 186 struct module *owner; /* Owner module for strings that don't then need freeing */ 187 char *buffer[8]; 188 }; 189 190 extern __attribute__((format(printf, 4, 5))) 191 void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...); 192 193 #define __logfc(fc, l, fmt, ...) logfc((fc)->log.log, NULL, \ 194 l, fmt, ## __VA_ARGS__) 195 #define __plog(p, l, fmt, ...) logfc((p)->log, (p)->prefix, \ 196 l, fmt, ## __VA_ARGS__) 197 /** 198 * infof - Store supplementary informational message 199 * @fc: The context in which to log the informational message 200 * @fmt: The format string 201 * 202 * Store the supplementary informational message for the process if the process 203 * has enabled the facility. 204 */ 205 #define infof(fc, fmt, ...) __logfc(fc, 'i', fmt, ## __VA_ARGS__) 206 #define info_plog(p, fmt, ...) __plog(p, 'i', fmt, ## __VA_ARGS__) 207 #define infofc(p, fmt, ...) __plog((&(fc)->log), 'i', fmt, ## __VA_ARGS__) 208 209 /** 210 * warnf - Store supplementary warning message 211 * @fc: The context in which to log the error message 212 * @fmt: The format string 213 * 214 * Store the supplementary warning message for the process if the process has 215 * enabled the facility. 216 */ 217 #define warnf(fc, fmt, ...) __logfc(fc, 'w', fmt, ## __VA_ARGS__) 218 #define warn_plog(p, fmt, ...) __plog(p, 'w', fmt, ## __VA_ARGS__) 219 #define warnfc(fc, fmt, ...) __plog((&(fc)->log), 'w', fmt, ## __VA_ARGS__) 220 221 /** 222 * errorf - Store supplementary error message 223 * @fc: The context in which to log the error message 224 * @fmt: The format string 225 * 226 * Store the supplementary error message for the process if the process has 227 * enabled the facility. 228 */ 229 #define errorf(fc, fmt, ...) __logfc(fc, 'e', fmt, ## __VA_ARGS__) 230 #define error_plog(p, fmt, ...) __plog(p, 'e', fmt, ## __VA_ARGS__) 231 #define errorfc(fc, fmt, ...) __plog((&(fc)->log), 'e', fmt, ## __VA_ARGS__) 232 233 /** 234 * invalf - Store supplementary invalid argument error message 235 * @fc: The context in which to log the error message 236 * @fmt: The format string 237 * 238 * Store the supplementary error message for the process if the process has 239 * enabled the facility and return -EINVAL. 240 */ 241 #define invalf(fc, fmt, ...) (errorf(fc, fmt, ## __VA_ARGS__), -EINVAL) 242 #define inval_plog(p, fmt, ...) (error_plog(p, fmt, ## __VA_ARGS__), -EINVAL) 243 #define invalfc(fc, fmt, ...) (errorfc(fc, fmt, ## __VA_ARGS__), -EINVAL) 244 245 #endif /* _LINUX_FS_CONTEXT_H */ 246