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 ([email protected]) 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_filename_empty, /* Value is a filename* + dirfd + AT_EMPTY_PATH */ 58 fs_value_is_file, /* Value is a file* */ 59 }; 60 61 /* 62 * Configuration parameter. 63 */ 64 struct fs_parameter { 65 const char *key; /* Parameter name */ 66 enum fs_value_type type:8; /* The type of value here */ 67 union { 68 char *string; 69 void *blob; 70 struct filename *name; 71 struct file *file; 72 }; 73 size_t size; 74 int dirfd; 75 }; 76 77 /* 78 * Filesystem context for holding the parameters used in the creation or 79 * reconfiguration of a superblock. 80 * 81 * Superblock creation fills in ->root whereas reconfiguration begins with this 82 * already set. 83 * 84 * See Documentation/filesystems/mount_api.txt 85 */ 86 struct fs_context { 87 const struct fs_context_operations *ops; 88 struct mutex uapi_mutex; /* Userspace access mutex */ 89 struct file_system_type *fs_type; 90 void *fs_private; /* The filesystem's context */ 91 struct dentry *root; /* The root and superblock */ 92 struct user_namespace *user_ns; /* The user namespace for this mount */ 93 struct net *net_ns; /* The network namespace for this mount */ 94 const struct cred *cred; /* The mounter's credentials */ 95 struct fc_log *log; /* Logging buffer */ 96 const char *source; /* The source name (eg. dev path) */ 97 const char *subtype; /* The subtype to set on the superblock */ 98 void *security; /* Linux S&M options */ 99 void *s_fs_info; /* Proposed s_fs_info */ 100 unsigned int sb_flags; /* Proposed superblock flags (SB_*) */ 101 unsigned int sb_flags_mask; /* Superblock flags that were changed */ 102 unsigned int s_iflags; /* OR'd with sb->s_iflags */ 103 unsigned int lsm_flags; /* Information flags from the fs to the LSM */ 104 enum fs_context_purpose purpose:8; 105 enum fs_context_phase phase:8; /* The phase the context is in */ 106 bool need_free:1; /* Need to call ops->free() */ 107 bool global:1; /* Goes into &init_user_ns */ 108 }; 109 110 struct fs_context_operations { 111 void (*free)(struct fs_context *fc); 112 int (*dup)(struct fs_context *fc, struct fs_context *src_fc); 113 int (*parse_param)(struct fs_context *fc, struct fs_parameter *param); 114 int (*parse_monolithic)(struct fs_context *fc, void *data); 115 int (*get_tree)(struct fs_context *fc); 116 int (*reconfigure)(struct fs_context *fc); 117 }; 118 119 /* 120 * fs_context manipulation functions. 121 */ 122 extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type, 123 unsigned int sb_flags); 124 extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry, 125 unsigned int sb_flags, 126 unsigned int sb_flags_mask); 127 extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type, 128 struct dentry *reference); 129 130 extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc); 131 extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param); 132 extern int vfs_parse_fs_string(struct fs_context *fc, const char *key, 133 const char *value, size_t v_size); 134 extern int generic_parse_monolithic(struct fs_context *fc, void *data); 135 extern int vfs_get_tree(struct fs_context *fc); 136 extern void put_fs_context(struct fs_context *fc); 137 138 /* 139 * sget() wrapper to be called from the ->get_tree() op. 140 */ 141 enum vfs_get_super_keying { 142 vfs_get_single_super, /* Only one such superblock may exist */ 143 vfs_get_keyed_super, /* Superblocks with different s_fs_info keys may exist */ 144 vfs_get_independent_super, /* Multiple independent superblocks may exist */ 145 }; 146 extern int vfs_get_super(struct fs_context *fc, 147 enum vfs_get_super_keying keying, 148 int (*fill_super)(struct super_block *sb, 149 struct fs_context *fc)); 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)); 156 157 extern const struct file_operations fscontext_fops; 158 159 /* 160 * Mount error, warning and informational message logging. This structure is 161 * shareable between a mount and a subordinate mount. 162 */ 163 struct fc_log { 164 refcount_t usage; 165 u8 head; /* Insertion index in buffer[] */ 166 u8 tail; /* Removal index in buffer[] */ 167 u8 need_free; /* Mask of kfree'able items in buffer[] */ 168 struct module *owner; /* Owner module for strings that don't then need freeing */ 169 char *buffer[8]; 170 }; 171 172 extern __attribute__((format(printf, 2, 3))) 173 void logfc(struct fs_context *fc, const char *fmt, ...); 174 175 /** 176 * infof - Store supplementary informational message 177 * @fc: The context in which to log the informational message 178 * @fmt: The format string 179 * 180 * Store the supplementary informational message for the process if the process 181 * has enabled the facility. 182 */ 183 #define infof(fc, fmt, ...) ({ logfc(fc, "i "fmt, ## __VA_ARGS__); }) 184 185 /** 186 * warnf - Store supplementary warning message 187 * @fc: The context in which to log the error message 188 * @fmt: The format string 189 * 190 * Store the supplementary warning message for the process if the process has 191 * enabled the facility. 192 */ 193 #define warnf(fc, fmt, ...) ({ logfc(fc, "w "fmt, ## __VA_ARGS__); }) 194 195 /** 196 * errorf - Store supplementary error message 197 * @fc: The context in which to log the error message 198 * @fmt: The format string 199 * 200 * Store the supplementary error message for the process if the process has 201 * enabled the facility. 202 */ 203 #define errorf(fc, fmt, ...) ({ logfc(fc, "e "fmt, ## __VA_ARGS__); }) 204 205 /** 206 * invalf - Store supplementary invalid argument error message 207 * @fc: The context in which to log the error message 208 * @fmt: The format string 209 * 210 * Store the supplementary error message for the process if the process has 211 * enabled the facility and return -EINVAL. 212 */ 213 #define invalf(fc, fmt, ...) ({ errorf(fc, fmt, ## __VA_ARGS__); -EINVAL; }) 214 215 #endif /* _LINUX_FS_CONTEXT_H */ 216